BLUETOOTH Low Energy (BLE)
Bluetooth Low Energy (also known as Bluetooth LE, BLE, and “BLUETOOTH Smart”) is a specification that enables radio frequency communication between various types of devices. One particular portion of the BLE standard is the advertiser/scanner model that allows a device designated as an advertiser device to broadcast information that can be received by one or more scanner devices. BLUETOOTH modules implementing a BLE standard are often integrated into various types of mobile devices that are battery powered.
BLE is used as a wireless personal area network technology. It is designed and marketed by the Bluetooth Special Interest Group (known as the “SIG”) and aimed at novel applications in the healthcare, fitness, beacons, security, and home entertainment industries.
Compared to Classic Bluetooth, Bluetooth Smart is intended to provide considerably reduced power consumption and cost while maintaining a similar communication range.
Accordingly, managing power consumption associated with the BLUETOOTH modules is one key performance concern as it pertains to battery life in mobile devices, including smartphones, wearables such as APPLE and ANDROID watches, FITBIT devices, laptop computers, tablet computing systems, and other electronic devices.
Bluetooth Beacons
Bluetooth Beacons are transmitters that use BLE to broadcast signals that can be detected by BLE compatible devices such as smartphones.
An increasing number of manufacturers are providing beacons to the marketplace. Among these are: BlueCats, BlueSense, Estimote, Gelo, Glimworm, Gimbal (by Qualcomm), Kontakt, Sensorberg and Sonic Notify.
IBEACON, an indoor positioning system from Apple Inc., uses BLE to transmit a Universally Unique Identifier (UUID), which is picked up by a compatible smartphone app or operating system on a mobile device. The device can then look up the identifier over the internet to determine the device's physical location or trigger an action on the device such as a check-in on social media or a push notification.
Various vendors (see above) have made hardware iBeacons that come in a variety of form factors, including small coin cell devices, USB sticks, and generic Bluetooth 4.0 capable USB dongles.
Many of these BLE beacons are relatively simple hardware devices that include a BLE System-on-Chip (SoC) device 110, a 2.45 GHz antenna 120, and a power source (not shown), as illustrated schematically as beacon 100 in FIG. 1. The antenna in such embodiments might be an omnidirectional PCB- or chip-based antenna. The battery source may be a coin cell, e.g., a CR2032 or Li-Ion/Li—Po battery pack. The BLE SoC is in some embodiments a single chip that contains a microcontroller, e.g., an ARM M0, running a BLE software stack; a radio frequency (RF) interface; and a number of peripherals.
Beacon Limitations for Location-Based Advertising
Received Signal Strength Indicator (RSSI) is a measurement of the power present in a received radio signal. RSSI measurements can be used by a smartphone or other BLE-enabled device to estimate the distance to the BLE beacon that transmitted the BLE signal.
In principle, being able to determine the distance from a smartphone to a particular beacon is very useful and has many commercial applications including location-based advertising. In practice, RSSI-based measurements have proven to be only an approximate measure of relative distance in location-based advertising applications. Distance estimations based on RSSI measurements are subject to a number of environmental factors that are difficult to account for during beacon design and installation, e.g., the presence of objects (other people, furniture, etc.) between the beacon and the smartphone.
Additionally, basic RSSI measurements do not indicate the direction between the beacon and smartphone—only distance. To date, determining position has been achieved by deploying multiple beacons in a location (e.g., shop or room) and using the RSSI data from all of the available beacons to triangulate position. The limitations of the RSSI method of determining distance and the need to deploy beacons at multiple locations makes this method undesirable in many applications.